Eusarcus longiceps nov. Page 257 1 Carapace of young specimen showing outline and position of lateral eyes. Natural size 2 Carapace of young specimen with traces of ornamentation 3 Well preserved specimen, showing marginal border and outline of ventral side (as darker rim). Probably somewhat compressed in posterior part. Natural size 4 Largest carapace observed. The lateral margin is partly folded under and the specimen appears therefore too narrow. The lateral eyes and ocelli are well preserved in the specimen; the former are somewhat displaced by the folding. Natural size 5 Carapace and preabdomen; the former apparently retaining the original outline. Type. The preabdomen is imperfect. Natural size 6 Large carapace with the marginal shield of the ventral side thrown outward in the posterior part. Natural size

Eocarcinosoma (Eusarcus) triangulatus nov. Page 258 7 Largest and most perfect carapace observed, apparently but little distorted and retaining the first tergite. Type. Natural size 8 Small carapace with fragment of first tergite. × 2 9 Carapace and preabdomen much distorted, but showing their great width. The swimming leg is too indistinct for accurate figuring. Natural size

Disjecta membra referable to Eusarcus 10 Metastoma, possibly belonging to Eusarcus longiceps. × 2 11, 12 Metastomas, possibly belonging to Eusarcus triangulatus. Natural size 13–16 Patches of integument exquisitely retaining the ornamentation. The latter exhibits considerable variation, recalling the ornamentation of Eusarcus and Echinognathus. Figure 13, × 4; figure 14, × 5; figure 15, × 2; figure 16, × 5 17 Portion of abdomen, comparable in outline to that of a Eusarcus. Natural size 18 Postabdominal segment, recalling that of a Eusarcus. Natural size 19, 20 Spines of endognathites, belonging to this genus, or to Echinognathus or Stylonurus. Natural size Horizon and locality. Lower Siluric: Schenectady shale. The originals of figures 1–7, 10, 11, 13–16, 18–20 are from the Dettbarn quarry at Schenectady, those of figures 8, 9 from Duanesburg, that of figure 12 from Rotterdam Junction and that of figure 17 from Aqueduct, all in Schenectady county. All originals are in the State Museum